Stable dental varnish compositions and methods of manufacture and use

ABSTRACT

Fluoride varnish compositions for temporary application and adhesion to a person&#39;s teeth include a carrier that remains stable and translucent during storage. The compositions include a carrier comprising a stable and translucent resin and a fluoride ion source (e.g., a fluoride salt such as sodium fluoride) dispersed within the carrier so as to provide biologically available fluoride ions to teeth being treated. The carrier resists formation of solids that can plug a 25 gauge (or 30 gauge) syringe brush applicator tip. The compositions may also include an adhesion promoting agent comprising an alkyl phosphoric acid. The composition adheres only temporarily to tooth tissue (e.g., for a period of at least about 4 minutes, but not more than about 1 year), after which the composition spontaneously wears away as a natural result of the action of the tongue, saliva and/or other factors.

This application is a division of U.S. patent application Ser. No.15/855,728, filed Dec. 27, 2017, which a continuation of U.S. patentapplication Ser. No. 14/775,470, filed Sep. 11, 2015, which is a 371application of International Application No. PCT/US14/25323, filed Mar.13, 2014, which claims the benefit of U.S. Provisional PatentApplication No. 61/794,767, filed Mar. 15, 2013, the disclosures ofwhich are incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION 1. The Field of the Invention

The present invention generally relates to dental treatmentcompositions, including fluoride treatment compositions.

2. The Relevant Technology

In the field of dentistry, fluoride compositions are applied to apatient's teeth as part of a routine dental cleaning. Application offluoride has been widely recognized as a method for preventing toothdecay. According to one method, a fluoride gel composition is dispensedwithin a dental tray, after which the tray is placed over the patient'steeth. The tray holds the fluoride gel composition adjacent to thepatient's teeth, and after a desired amount of time (e.g., a minute orless), the tray is removed and the remaining gel composition is rinsedoff the patient's teeth.

Alternatively, fluoride varnish compositions can be applied to aperson's teeth and left in place for days or weeks. In many casesfluoride varnish compositions are yellow or opaque white and thereforeare not aesthetically pleasing. In addition, fluoride varnish aretypically dispensed from a container using a brush. The practitionertypically dips the brush into the container and then paints the fluoridevarnish onto the patient's teeth like fingernail polish. This dippingand painting procedure is repeated several times, perhaps once for eachtooth, which made the procedure cumbersome and potentially messy.

And while it may be desirable to dispense a fluoride varnish compositionfrom a syringe and onto a patient's teeth using a brush tip, existingfluoride compositions have lacked sufficient stability and shelf life toremain as a stable gel over time during storage and prior to use. As aresult, they can become gritty over time, which causes plugging of thebrush tip, especially narrow gauge tips that are suitable for dispensingrelatively low viscosity fluids such as fluoride varnish compositions.Formation of solids also reduces initial translucency and causesfluoride varnish compositions to become hazy or white over time,reducing their aesthetic appeal.

SUMMARY

Disclosed herein are stable dental varnish compositions for applicationto a person's teeth, which comprise a stable liquid or gel carrier andan active agent dispersed within the carrier. The carrier includes asolvent, a resin component and an acidifying component. The resincomponent comprises an acidic hydrogenated wood rosin that has been atleast partially neutralized to raise its pH to above 5. The acidifyingcomponent comprises at least organic or inorganic acid that lowers thepH of the liquid or gel carrier to below 5.

The dental varnish compositions can be formulated to be stable for atleast about 3 months so as to remain translucent and not form solidsthat plug a 25 gauge (or smaller) syringe brush applicator tip.According to one embodiment, the dental varnish composition can bestable for at least about 6 months so as to remain translucent and notform solids that plug a 30 gauge (or smaller) syringe brush applicatortip.

According to one embodiment, the dental varnish composition may furthercomprise an organo phosphoric acid having at least one alkyl group. Theorgano phosphoric acid can be useful to increase adhesion of the varnishcomposition to a tooth surface.

According to one embodiment, the active agent comprises a fluoride ionsource so that the dental varnish composition is a fluoride varnish.Alternatively, or in addition to fluoride ions, the active agent mayinclude at least one of a calcium ion source or a phosphate ion source.If the fluoride varnish composition is anhydrous, premature reaction andprecipitation of fluoride and calcium ions is minimized or prevented.

A method of manufacturing a stable dental varnish composition forapplication to a person's teeth comprises: (1) preparing a stable liquidor gel carrier by mixing together an acidic hydrogenated wood rosin thathas been at least partially neutralized to raise its pH to above 5, asolvent, and an acidifying agent to lower the pH of the carrier to below5; and (2) adding an active agent before, during or after formation ofthe stable liquid or gel carrier.

These and other benefits, advantages and features of the presentinvention will become more fully apparent from the following descriptionand appended claims, or may be learned by the practice of the inventionas set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above recited and other benefits,advantages and features of the invention are obtained, a more particulardescription of the invention briefly described above will be rendered byreference to specific embodiments thereof which are illustrated in theappended drawings.

Understanding that these drawings depict only typical embodiments of theinvention and are not therefore to be considered limiting of its scope,the invention will be described and explained with additionalspecificity and detail through the use of the accompanying drawings, inwhich:

FIG. 1 is a perspective view of an exemplary two-syringe closed vesselmixing system that contains a multi-part fluoride varnish composition;

FIGS. 2A-2B depict the exemplary closed vessel mixing system of FIG. 1being used to cycle the multi-part fluoride varnish composition back andforth;

FIGS. 3A-3B illustrate a syringe (e.g., from the mixing system ofFIG. 1) being coupled to a flocked applicator tip; and

FIG. 4 illustrates the application of a fluoride varnish composition toa tooth using a flocked applicator tip.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Introduction

Disclosed herein are stable dental varnish compositions for use inproviding a desired treatment to a person's teeth. The stable dentalvarnish compositions include a liquid or gel carrier that is formulatedso that the dental varnish composition remains stable and translucentover time (e.g., for at least about 3 months) and does not form solidsthat plug a 25 gauge (or smaller) syringe brush applicator tip.Surprisingly, increased stability is provided by formulating the liquidor gel carrier to include an acidic hydrogenated wood rosin that hasbeen at least partially neutralized with a base to raise its pH to above5 (e.g., to about 6-7) and then acidifying the carrier to below 5 (e.g.,to about 4 or less). Dental varnish compositions prepared in this mannerhave substantially greater stability over time compared to varnishcompositions made using an acidic hydrogenated wood rosin that has notbeen neutralized. Such increased stability is achieved even whenacidification of the neutralized hydrogenated wood rosin causes thecomposition to have the same pH as a composition made using acidichydrogenated wood rosin that is not neutralized with a base.

II. Exemplary Dental Varnish Compositions

Exemplary dental varnish compositions as disclosed herein include astable liquid or gel carrier and an active agent dispersed within thecarrier, a stable liquid or gel carrier and an active agent dispersedwithin the carrier. The carrier typically comprises a solvent, a resincomponent and an acidifying component. The resin componentadvantageously includes an acidic hydrogenated wood rosin that has beenat least partially neutralized to raise its pH to above 5. Theacidifying component may include at least organic or inorganic acidincluded in an amount in order to lower the pH of the liquid or gelcarrier to below 5.

An example of a suitable resin component is Foral® NC synthetic resin,which is manufactured by Pinova, Inc., Bruswick, Ga., USA, and is thepartial sodium resinate of the highly hydrogenated wood rosin, Foral® AXresin, also manufactured by Pinova, Inc. Foral® AX is a thermoplastic,acidic resin produced by hydrogenating wood rosin to a high degree.According to Product Data Sheet, Foral® AX Synthetic Resin, provided byPinova, Inc., http://www.pinovasolutions.com/docs/Foral%20AX.pdf, Foral®AX is the “most highly stabilized rosin commercially available”.Compared to a competitor's resin, Foral® AX “has better initial colorand color retention, and even greater resistance to oxidation”. Id.Foral Foral® AX acidic hydrogenated wood rosin has a softening point(Ring & Ball, minimum) of 66° C., a color (USRG rosin scale, maximum) ofXB, an acid number (minimum) of 158 mg KOH/g, an abietic acid (UV,maximum) value of 0.2%, and refractive index at 100° C. (maximum) of1.4970. Id.

By way of comparison, Foral® NC is similar to Foral® AX except that an“added benefit of the partial sodium neutralization is an increase insoftening point and glass transition temperatures, which allows Foral NCto be packaged as free-flowing pastilles in easily handled bags.”Product Data Sheet, Foral® NC Synthetic Resin, provided by Pinova, Inc.,http://www.pinovasolutions.com/docs/Foral%20NC.pdf. Foral Foral® NCsodium resinate of the highly hydrogenated wood rosin Foral AX has asoftening point (Ring & Ball) of 78-92° C. (typically 83° C.), a color(USRG, maximum) of X (typically XB), an acid number of 120-138 mg KOH/g(typically 126 mg KOH/g), and a typical abietic acid value of <2%. Id.

When formulating dental varnish compositions using Foral® AX as the solehydrogenated rosin, the resulting varnish has a pH of about 3. Suchvarnish compositions are initially highly translucent and have good flowproperties, which permits them to be dispensed through a narrow gaugesyringe brush tip onto a person's tooth surfaces. However, after a fewmonths (e.g., 3 months), such dental varnish compositions can formprecipitates, which can cause them to become gritty and lesstranslucent, causing loss of aesthetic appeal and, worse, plugging ofthe syringe brush applicator tip. By comparison, substituting at least aportion of the Foral® AX with Foral® NC, which is less acidic and has ahigher pH, and then adding an acid to lower the pH so that the varnishcomposition has the same or similar pH as varnishes made using Foral® AXas the sole hydrogenated rosin results in a varnish composition that issubstantially more stable over time. Substituting at least a portion ofForal® AX with Foral® NC and then acidifying the composition to havesame low pH unexpectedly reduces or eliminates formation of precipitatesthat reduce translucency and cause syringe tip plugging. This result issurprising and unexpected and would not be predicted based on acomparison of the Product Data Sheets of these products provided byPinova, Inc.

Example acids that can be used to lower the pH of the liquid or gelcarrier containing a base neutralized acidic hydrogenated wood rosininclude organic acids and inorganic acids, such as citric acid,phosphoric acid, boric acid, malic acid, and the like. The acid can beadded in order to adjust the pH of the liquid or gel carrier containinga base neutralized acidic hydrogenated wood rosin to less than 5,preferably less than about 4.5, more preferably less than about 4, andmost preferably to less than about 3.5. According to one embodiment, thepH can be lowered to about 3 or below.

The dental varnish compositions can be formulated to be stable for atleast about 3 months so as to remain translucent and not form solidsthat plug a 25 gauge (or smaller) syringe brush applicator tip.According to one embodiment, the dental varnish composition can bestable for at least about 6 months so as to remain translucent and notform solids that plug a 30 gauge (or smaller) syringe brush applicatortip.

In addition to the main resin component, which is the aforementionedacidic hydrogenated wood rosin that has been at least partiallyneutralized to raise its pH to above 5, the dental varnish compositionmay optionally include one or more auxiliary resins. Examples ofauxiliary resins include natural resins, non-hydrogenated wood rosins,acidic hydrogenated wood rosins, synthetic resins, colophonium, shellac,and combinations thereof. The auxiliary resins are typicallyhydrophobic, substantially insoluble in water, and freely soluble inalcohol, benzene, ether, glacial acetic acid, oils, and carbondisulfide. Various materials that are individually referred to as“colophonium” include Canadian balsam, Olibanum balsam, Elemi resin,Opopanax resin, Tolu balsam, Peruvian balsam, and Poly-Pale™ resin,which is a partially dimerized rosin available from Eastman Chemical,located in Kingsport, Tenn. Examples of hydrogenated wood rosins includethe aforementioned Foral® AX, a fully hydrogenated tree rosin,Staybelite® resin, a partially hydrogenated wood rosin, and Endere® S, ahighly hydrogenated allergen tested resin from wood rosin feedstock.Other rosins or rosin derivatives include Pexite® FF, an acidic resinextracted from pine tree stumps, Pexalyn® 295, a synthetic, acidfunctionalized resin from wood rosin feedstock, Pentalyn® FC, apentaerythritol ester of maleic anhydride-modified wood rosin,Staybelite® Ester 10-A, an ester of hydrogenated rosin, Hercolyn® D, amethyl ester of hydrogenated wood rosin, Pentalyn® H-A, apentaerythritol ester of hydrogenated rosin.

The one or more resin components may be included in the dental varnishcompositions in various amounts, such as in an amount in a range ofabout 20% to about 90% by weight, preferably in a range of about 25% toabout 80% by weight, more preferably in a range of about 35% to about75% by weight, and most preferably in a range of about 40% to about 70%by weight.

Dental varnish compositions as disclosed herein may include any desiredactive agent. For example, the active agent can be a fluoride ion sourcethat provides fluoride treatment to a person's tooth. Instead of or inaddition to the fluoride ion source, the active agent may comprise acalcium ion source and/or a phosphate ion source. Even though calciumions and fluoride ions can react in water to form an insoluble calciumfluoride precipitate, providing a dental varnish composition that isanhydrous (e.g., so as to have a water content of less than 2%,preferably less than about 1.5%, more preferably less than about 1%, andmost preferably less than about 0.5%) prevents premature reaction andprecipitation. Once applied to a person's teeth, such reaction canbeneficially occur on or in the teeth in the presence of saliva.

Examples of fluoride ion sources include sodium fluoride, BiF₃, SnF₂,ZnF₂, KF, CaF₂, ZrF₄, sodium mono-fluorophosphate (Na₂FPO₃),hexafluorosilicic acid, sodium hexafluorosilicate, or combinationsthereof. When included, the fluoride ion source (e.g., sodium fluoride)may be included in an amount in a range of about 0.1% to about 10% byweight, preferably in a range of about 1% to about 8% by weight, andmore preferably in a range of about 2.5% to about 7% by weight.

Examples of calcium and phosphate ion sources include calcium phosphate,calcium nitrate, calcium glycerophosphate, calcium gluconate, calciumchloride, sodium phosphates, sodium polyphosphates, sodiumpyrophosphates, and potassium phosphates. Calcium and phosphate ionsources, when included, can be in a range of about 0.1-5% by weight ofthe varnish composition.

According to one embodiment, the dental varnish composition may furtherinclude an organo phosphoric acid (or phosphoric acid ester) that canenhance adhesion of the dental varnish composition to tooth surfaces.The organo phosphoric acid can comprise an alkyl phosphoric acid (alsoreferred to as an alkyl phosphoric acid ester) having from 3 to about 30carbon atoms in the alkyl group. Mono-alkyl phosphoric acid esters areparticularly useful, although di-alkyl phosphoric acid components mayalternatively and/or additionally be used. The generic chemicalstructure of an exemplary organo phosphoric acid is as follows:

“R” represents an alkyl group, which may have from 3 to about 30 carbonatoms. More preferably the alkyl group may include from about 5 to about30 carbon atoms, more preferably from about 10 to about 25 carbon atoms,and most preferably from about 15 to about 22 carbon atoms. Hexadecylphosphoric acid (also referred to as hexadecane phosphate) (having 16carbon atoms) and docosyl phosphoric acid (having 22 carbon atoms) havebeen found to provide excellent adhesion properties to the carrier.Docosyl phosphoric acid is also believed to exhibit anti-microbial(specifically anti-viral) properties. Structures for both hexadecylphosphoric acid and docosyl phosphoric acid, respectively, are shownbelow:

According to one embodiment, the alkyl groups can be fully saturated sothat they contain no polymerizable groups as the compositions areintended to adhere relatively weakly to the tissue, not form a permanentbond with underlying tooth tissue. It is believed that the hydrophilicphosphoric acid groups have an affinity (e.g., through hydrogen bondingand/or ionic forces) to hydrophilic tooth surfaces, which contain highquantities of minerals (e.g., calcium-based minerals).

Although adhesion promoting agents having alkyl groups with from 3 toabout 30 carbon atoms have been found to be useful, it may be possibleto employ an adhesion promoting agent having at least one alkyl groupthat includes significantly more carbon atoms. For example, it may bepossible to use alkyl groups up to one thousand, ten thousand, or even100,000 or more by diluting the adhesion promoting agent withappropriate solvents.

When included, the organo phosphoric acid component may be included inany desired amount, for example in a range of about 0.5% to about 40% byweight, preferably in a range of about 1% to about 30% by weight, morepreferably in a range of about 3% to about 20% by weight, and mostpreferably in a range of about 5% to about 15% by weight. The use ofhigher molecular weight, longer alkyl chain adhesion promoting agentsmay require relatively lower concentrations, which may even be less than0.5% depending on the degree of dilution (e.g., with a solvent) requiredto form a composition having the desired consistency.

The liquid or gel carrier will typically include one or more solventsinto which the resin materials are dissolved to provide a varnishcomposition having a desired consistency and flow properties. Ethanol isa useful solvent as it is non-toxic and generally safe for use in theoral cavity, although other solvents (e.g., acetone or isopropylalcohol) could alternatively be used. If included, the solvent istypically selected so that it evaporates relatively quickly after thecomposition is applied to the teeth in order for the dental varnishcomposition to form a film of solid varnish material on the toothsurface. The one or more solvents are typically included in an amount ina range of 5% to about 75% by weight, preferably in a range of about 10%to about 60% by weight of the composition, more preferably in a range ofabout 15% to about 50% by weight, and most preferably in a range ofabout 20% to about 45% by weight.

One or more solubilizing agents, such as one or more polyoxyethyleneemulsifiers (e.g., polysorbates), may advantageously be included to helpprevent phase separation of the various carrier components. Exemplarysolubilizing agents include various polysorbates (e.g., polysorbate 20,polysorbate 40, polysorbate 60, polysorbate 80), although otheremulsifiers may also be used. Polysorbate 80 (e.g., Tween® 80), whichincludes a monooleate type fatty acid associated with thepolyoxyethylene sorbitan part of the molecule, is a particularly usefulsolubilizing agent. The one or more solubilizing agents may be includedin an amount in a range of about 0.001% to about 3% by weight,preferably in a range of about 0.01% to about 1% by weight, and morepreferably in a range of about 0.1% to about 0.5% by weight.

Examples of flavorants that may be included are bubble gum, peach,tropical punch, grape, watermelon, lemon-lime, cinnamon, methylsalicylate, natural wintergreen, natural cool mint, natural wintermint,peppermint ocean, and/or crème de menthe. Examples of sweeteners includesucralose, xylitol, sodium saccharine, aspartame, and stevia.Furthermore, xylitol has been found to exhibit antimicrobial effects.Flavorant(s), sweetener(s), and colorant(s) may each be included in anamount in a range of about 0.1% to about 10% by weight, preferably fromabout 0.5% to about 8% by weight, and more preferably from about 1% toabout 5% by weight.

A rheology modifying agent may also be included if desired. Fumed silicais a useful rheology modifying agent and has been found to thicken thecomposition for improved handling, as well as reducing the tendency ofinsoluble fluoride salts to settle during storage. Rheology modifyingcomponent(s) may be included in an amount in a range of about 0.1% toabout 10% by weight, preferably in a range of about 0.5% to about 8% byweight, and more preferably in a range of about 1% to about 5% byweight.

Advantageously, the dental varnish compositions are sufficientlyadhesive so as to allow the practitioner to brush, paint, or otherwiseapply the composition onto a patient's teeth without having to worryabout the composition running or dripping off. Exemplary adhesivecompositions may have a relatively low viscosity (e.g., less than about1000 centipoise). For example, the dental varnish compositions may havea viscosity of about 200 centipoise to about 800 centipoise, preferablyabout 300 centipoise to about 600 centipoise.

The dental varnish compositions can be formulated to temporarily adhereto tooth tissue (e.g., for a period of at least about 4 minutes, but notmore than about 1 year, more typically about 5 minutes to about 90 days,more typically about 30 minutes to about 5 days). Over time, the varnishcomposition can spontaneously wear away as a natural result of theaction of the tongue, saliva and/or other factors. The varnishcomposition may also be removed by applying mechanical action, forexample, by brushing.

III. Exemplary Mixing Systems and Methods

FIG. 1 illustrates a syringe-to-syringe mixing system 100 for mixing adental varnish composition preparatory to applying it to a person'steeth. Mixing system 100 includes a first syringe 102 a coupleable to asecond syringe 102 b. First syringe 102 a includes a first barrel 104 aand a first plunger 106 a slidably disposed within first barrel 104 a.First plunger 106 a forms a seal against the inner wall of first barrel104 a, allowing plunger 106 a to push the contents of barrel 104 a outof the barrel. Second syringe 102 b includes a second barrel 104 b and asecond plunger 106 b disposed within second barrel 104 b. First syringe102 a and second syringe 102 b are illustrated as being coupled togetherso as to allow the dental varnish composition 108 to be cycled back andforth between the syringes so as to substantially suspend any solidparticles (e.g., insoluble fluoride salts, calcium ion salts, and/orphosphate ions salts) phase within a generally hydrophobic liquidcarrier phase of the composition.

As illustrated in FIGS. 2A and 2B, a dental practitioner is able toapply turbulence to the multi-phase dental varnish composition 108within first and second syringes of system 100 by manipulating plungers106 a and 106 b so as to cycle the varnish composition 108 back andforth. In such a mixing system the dental varnish composition may becycled back and forth as many times as desired so as to substantiallysuspend the solid particle phase within the liquid phase of thecomposition.

System 100 may advantageously be configured so as to contain a singleuse quantity of the multi-phase dental varnish composition 108. Such asystem advantageously provides a single use system that can be providedto the dental practitioner as a uni-dose system which can be mixed andapplied to the teeth of a single patient, after which the emptysyringe-to-syringe mixing apparatus can be discarded.

Such a syringe-to-syringe configuration is effective in suspendinginsoluble particulate components of the composition within the carrieras particles (e.g., fluoride salts) may tend to settle out duringstorage. The inclusion of fumed silica within the composition may reduceor eliminate settling. In addition, the syringe-to-syringe configurationis effective in mixing together any other components of the varnishcomposition that may tend to form separate phases during prolongedstorage. For example, compositions not including a solubilizing agent(e.g., polysorbate 80) to help prevent the resin from separating fromother components of the carrier may tend to form separate phases duringstorage. If such is the case with any given varnish composition, thesyringe-to-syringe configuration allows for quick and easy remixing ofthe composition prior to application to a patient's teeth.

Once the solid particles (e.g., fluoride salt) has been suspended, thedental varnish composition may be applied to a person's teeth. Accordingto one method, as seen in FIGS. 3A-3B, an applicator tip 150 may becoupled to syringe 102 a containing the varnish composition 108 afterthe syringe has been separated from the remainder of the mixing system.Tip 150 may be coupled to first syringe 102 a so as to allow a dentalpractitioner to dispense dental varnish composition 108 onto a person'steeth. As illustrated, applicator tip 150 may include a flocked tip 152so as to allow the user to paint the composition 108 onto the teeth. Useof an applicator tip 150 including a flocked tip 152 are particularlyuseful, although other types of tips (e.g., a tip including a foam pad,a cotton swab, or other absorbent material) can be used.

FIG. 4 illustrates a dental practitioner using applicator tip 150 toapply varnish composition 108 to a person's tooth 160. Dental varnishcomposition 108 may be substantially colorless or, alternatively, it mayprovide a visual contrast against the surface of a person's teeth toallow a dental practitioner to easily determine where the compositionhas been applied. Suspension of the particulate phase (and/or remixingof other components) advantageously provides an even distribution of theactive agent (e.g., fluoride salt), carrier, and other components to theteeth, providing a more consistent concentration of active agent andmore consistent adhesion characteristics, resulting in overall bettertreatment across the full surface area of the tooth being treated.Although dispensing and application of the varnish composition isdescribed using syringe-to syringe mixing device 100, it is understoodthat any apparatus or method of application may be used. Alternativedevices that can be used to suspend and dispense the fluoride varnishcomposition are disclosed in U.S. patent application Ser. No. 11/348,055filed Feb. 6, 2006 and entitled METHODS AND SYSTEMS FOR MIXING AMULTI-PART FLUORIDE VARNISH COMPOSITION, and U.S. patent applicationSer. No. 12/258,746 filed Oct. 27, 2008 entitled MIXING DEVICE INCLUDINGA PLUNGING MIXING MEMBER FOR USE WITH A SYRINGE, each of which isincorporated herein by reference.

The dental varnish composition can be formulated to remain adhered to aperson's teeth for an extended period of time relative to typicalin-office fluoride treatments, yet still be temporary. For example, thevarnish may remain adhered for at least about 4 minutes, but no morethan about 1 year, more preferably at least about 5 minutes but not morethan about 90 days. In one embodiment, the varnish composition mayremain adhered to a person's teeth for at least about 30 minutes,preferably at least about 2 hours, more preferably at least about oneday, and most preferably at least about two days. Nevertheless, suchcompositions may wear away in about 5 days or less. Advantageously, thevarnish composition can spontaneously wear away as a natural result ofthe action of the tongue, saliva and/or other factors within a temporaryperiod, typically no more than about 5 days. Of course, the compositionmay be removed earlier than it would wear away naturally, for example,by aggressive brushing. A small fraction of the varnish composition mayremain adhered to interproximal spaces between teeth (e.g., as long as7-10 days) absent removal by aggressive brushing and/or flossing.

Extended adherence by the varnish composition to tooth tissue isadvantageous as the tooth tissues can be exposed to the active agent(e.g., fluoride ions) for significantly longer times than is possiblewith in-office treatments or other treatments in which exposure to teethis significantly less than what is provided by the disclosed varnishcompositions. In particular, extended adherence to interproximal spacesbetween teeth may be particularly advantageous as these locations oftenharbor tooth decay.

IV. Examples

Following are examples of dental varnish compositions within the scopeof the disclosure, most of which have been found to be stable over timeso as resist formation of precipitates or other solids that can plug asyringe brush applicator tip, as well as a comparative example of acomposition that is not stable over time but can result in plugging of asyringe brush applicator tip after storage for several months.

Examples 1-7

Examples 1-7 illustrate the beneficial effect of substituting at least aportion of Foral® AX acidic hydrogenated wood rosin with Foral® NC, thesodium neutralized form of acidic hydrogenated wood rosin, and thenadding an acid to lower the pH. The composition of Example 1 includesForal® AX acidic hydrogenated wood rosin as the sole resin component.This composition is very translucent and flowable when initiallymanufacture but over time (e.g., 3 months or more) can become lesstranslucent (e.g., white) and gritty. In some cases, depending on thesize or gauge of the syringe brush applicator tip, the composition ofExample 1 can plug the applicator tip.

Component Example (Mass %) 1 2 3 4 5 6 7 Foral ® AX 60.9995 28.27 54.651.6 49.51 25.25 Foral ® NC 49.39 28.27 7 7.75 8.1 8.5 Pexite FF 2.241.25 25.25 Pexalyn 295 Pentalyn FC 1.25 Enderes S 10 Stayelite Ester10-A Hercolyn D 5 5 Pentalyn H-A Ethyl Alcohol 100% 23.9 19 25 25.2825.28 25.28 25.29 Hexadecane 5 5 5 5 5 5 5 phosphate Sodium Fluoride 5 55 5 5 5 5 Sucralose Powder 0.5 0.5 0.5 0.5 0.5 0.4 0.4 Saccharin 0.080.08 Xylitol 0.5005 0.01 0.01 0.01 0.02 0.01 0.01 Stevia 0.01 0.01Citric Acid 3 0.35 Phosphoric Acid 0.01 0.01 Boric Acid 0.01 0.1Polysorbate 80 0.1 0.1 0.1 0.1 0.01 0.01 0.11 (Tween 80) PeppermintOcean 3 2.5 2.5 2.5 Natural Wintermint 0.65 0.65 0.65 Natural Cool Mint2.7 2.7 2.7 Methyl Salicylate 0.65 0.65 0.65

The varnish compositions of Examples 2-7 remained more translucent andresisted formation of grittiness over time as compared to Example 1.

Component Example (Mass %) 8 9 10 11 12 13 14 Foral ® AX 25.25 5.5 6.5Foral ® NC 8.5 8.5 8.5 16 18.5 18.5 21.94 Pexite FF 25.25 25.25 14.2323.8 Pexalyn 295 23.25 20.14 15.1 Pentalyn FC 23.25 20.14 10.7 10.6 5.1Enderes S 1.1 1.1 0.9 5 7 6.5 Stayelite Ester 10-A 1.6 Hercolyn D 0.50.5 1 Pentalyn H-A 2 2 2 4.5 2.5 1 Ethyl Alcohol 100% 25.17 23.84 25.1726.17 26.15 25.92 25.05 Hexadecane 5 5 5 5 5 5 5 phosphate SodiumFluoride 5 5 5 5 5 5 5 Sucralose Powder 0.4 0.4 0.4 0.5 0.5 0.5 0.4Saccharin 0.08 0.08 0.08 Xylitol 0.01 0.01 0.03 0.03 0.03 0.01 Stevia0.01 0.01 0.02 0.01 Citric Acid 0.1 0.2 0.3 0.3 0.4 0.5 1.5 PhosphoricAcid 0.01 0.01 0.01 0.02 Boric Acid 0.01 0.02 0.5 Polysorbate 80 0.120.1 0.12 0.1 0.1 0.2 0.2 (Tween 80) Peppermint Ocean 3 3 3 NaturalWintermint 0.65 0.65 0.65 0.55 Natural Cool Mint 2.7 2.7 2.7 1.9 MethylSalicylate 0.65 0.65 0.65 0.55

The varnish compositions of Examples 8-14 remained more translucent andresisted formation of grittiness over time as compared to Example 1.

Component Example (Mass %) 15 16 17 18 19 20 21 Foral ® AX 20 18 18 6.75Foral ® NC 29.09 30.99 33 36 38.5 38.5 45.5 Pexite FF 10 7.5 Pexalyn 2955.1 Pentalyn FC 5.1 4.9 4.9 5.25 Enderes S 2.84 5.9 5.9 5.9 4.47 4.47Stayelite Ester 10-A 2.84 8.5 Hercolyn D 1.5 1 0.75 2 2 Pentalyn H-A 0.51 2 2 1.25 Ethyl Alcohol 100% 25.05 25.05 25.05 25.05 25.05 25.05 25.05Hexadecane 5 5 5 5 5 5 5 phosphate Sodium Fluoride 5 5 5 5 5 5 5Sucralose Powder 0.5 0.5 0.6 0.6 0.6 0.6 0.6 Saccharin Xylitol 0.01 0.010.01 0.01 0.01 0.01 0.01 Stevia Citric Acid 2.2 2.3 2.3 2.4 2.4 2.4 2.6Phosphoric Acid 0.01 0.01 0.01 0.02 Boric Acid 0.01 0.01 0.01 0.01Polysorbate 80 0.2 0.2 0.2 0.2 0.2 0.2 0.1 (Tween 80) Peppermint OceanNatural Wintermint 0.55 0.55 0.6 0.6 0.6 0.6 0.6 Natural Cool Mint 1.91.9 1.82 1.82 1.82 1.82 1.82 Methyl Salicylate 0.55 0.55 0.5 0.5 0.5 0.50.5

The varnish compositions of Examples 15-21 remained more translucent andresisted formation of grittiness over time as compared to Example 1.

Component Example (Mass %) 22 23 24 25 26 27 28 Foral ® AX 5.75 1.361.36 Foral ® NC 46.92 50.5 57.43 60 61.5 50.25 47.5 Pexite FF 3.75Pexalyn 295 Pentalyn FC Enderes S 4.47 8.43 1.5 10 10 Stayelite Ester10-A 2 2 2 Hercolyn D 2 2 1 1 1 1 Pentalyn H-A 1 1 1 1 Ethyl Alcohol100% 25.05 20.75 22.75 19.67 19.78 19.78 18.78 Hexadecane 5 5 5 5 5 5 5phosphate Sodium Fluoride 5 5 5 5 5 5 5 Sucralose Powder 0.6 0.6 0.6 0.50.5 0.5 0.5 Saccharin Xylitol 0.01 0.01 0.01 0.01 0.01 0.01 0.01 SteviaCitric Acid 2.6 3 3 3.1 3.1 3 3 Phosphoric Acid Boric Acid 0.01 0.010.02 0.01 Polysorbate 80 0.1 0.2 0.2 0.2 0.1 0.1 0.1 (Tween 80)Peppermint Ocean 2.5 2.5 2.5 2.5 3 3 3 Natural Wintermint Natural CoolMint Methyl Salicylate

The varnish compositions of Examples 22-28 remained more translucent andresisted formation of grittiness over time as compared to Example 1.

The compositions made according to Examples 2-28 are very similar to thecomposition of Example 1 in that they all include similar amounts ofwood rosin derivatives. However, Examples 2-28 all included some amountof Foral® NC, which, surprisingly and unexpectedly, yielded varnishcompositions that were more stable, translucent and less gritty overtime as compared to the varnish of Example 1. This was so even thoughExamples 2-28 were acidified using one or more acids in order to reducethe pH to the same of similar pH as Example 1. Thus, neutralizing highlyacidic hydrogenating wood rosin using a base such as sodium carbonateand then re-acidifying the neutralized hydrogenating wood rosin resultedin a highly hydrogenated and acidic wood rosin that neverthelessremained more stable over time.

It will be appreciated that the present claimed invention may beembodied in other specific forms without departing from its spirit oressential characteristics. The described embodiments are to beconsidered in all respects only as illustrative, not restrictive. Thescope of the invention is, therefore, indicated by the appended claimsrather than by the foregoing description. All changes that come withinthe meaning and range of equivalency of the claims are to be embracedwithin their scope.

What is claimed is:
 1. A method of manufacturing a dental varnishcomposition, comprising: obtaining a resin comprised of an acidichydrogenated wood rosin having an initial pH when measured in water andthat has been at least partially neutralized with a base so that theresin has a pH when measured in water that is higher than the initialpH; and combining the resin with an organic solvent, an active agent,and an acidifying component to acidify the dental varnish composition soas to have a pH when measured in water that is lower than the pH of theresin.
 2. The method of claim 1, wherein the acidic hydrogenated woodrosin has an initial pH when measured in water of less than 5 prior tobeing at least partially neutralized with the base, and wherein the atleast partially neutralized hydrogenated wood rosin has a pH whenmeasured in water of at least
 6. 3. The method of claim 1, wherein theacidifying component comprises at least one of an organic acid or aninorganic acid.
 4. The method of claim 3, wherein the acidifyingcomponent comprises an acid selected from the group consisting of citricacid, phosphoric acid, boric acid, malic acid, and mixtures thereof. 5.The method of claim 1, wherein the resin has a pH when measured in waterof at least 6 prior to adding the acidifying component, and wherein theacidifying component is added in an amount to adjust the pH of thedental varnish composition to less than 5 when measured in water.
 6. Themethod of claim 5, wherein the acidifying component is added in anamount to adjust the pH of the dental varnish composition to 4 or lesswhen measured in water.
 7. The method of claim 1, wherein the resincomprises the acidic hydrogenated wood rosin that has been at leastpartially neutralized with a base as a first resin component and anacidic hydrogenated wood rosin that has not been at least partiallyneutralized as a second resin component.
 8. The method of claim 1,further comprising placing the dental varnish composition into asyringe.
 9. The method of claim 1, wherein the dental varnishcomposition forms fewer solids and/or has less grittiness over timecompared to a dental varnish composition in which the resin consists ofan acidic hydrogenated wood rosin that has not been at least partiallyneutralized with a base.
 10. The method of claim 1, wherein the dentalvarnish composition resists formation of solids and/or grittiness for atleast about 3 months.
 11. The method of claim 1, wherein the dentalvarnish composition resists formation of solids and/or grittiness for atleast about 6 months.
 12. The method of claim 1, wherein the organicsolvent comprises at least one of ethanol, acetone, or isopropylalcohol.
 13. The method of claim 1, wherein the dental varnishcomposition is substantially anhydrous, and wherein the dental varnishhas a pH of less than 5 when measured after being placed onto teeth andexposed to saliva.
 14. The method of claim 1, wherein the active agentcomprises at least one of fluoride ion source, a calcium ion source, ora phosphate ion source.
 15. The method of claim 1, wherein the dentalvarnish composition is a liquid or gel.
 16. A method of manufacturing adental varnish composition, comprising: obtaining a first resincomponent comprised of acidic hydrogenated wood rosin; obtaining asecond resin component comprised of an acidic hydrogenated wood rosinthat has been at least partially neutralized with a base; and combiningthe first resin component and the second resin component with an organicsolvent, an active agent, and an acidifying component to acidify thedental varnish composition to a pH when measured in water that is lowerthan a pH of the second resin component.
 17. The method of claim 16,wherein the dental varnish composition is substantially anhydrous. 18.The method of claim 16, wherein the second resin component initially hasa pH when measured in water of at least 6, and wherein the acidifyingcomponent is added in an amount that adjusts the pH of the dentalvarnish composition to less than 5 when measured in water.
 19. A methodof manufacture a dental varnish composition, comprising: obtaining aresin comprised of an acidic hydrogenated wood rosin that has been atleast partially neutralized with a base; and combining the resin with anorganic solvent, an active agent, and an acidifying component to acidifyand form the dental varnish composition, wherein the dental varnishcomposition is substantially anhydrous, wherein the at least partiallyneutralized hydrogenated wood rosin has a pH when measured in water ofat least 6, and wherein the acidifying component is added in an amountthat adjusts the pH of the dental varnish composition to less than 5when measured in water.